JPS588691B2 - Polyethylene manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyethylene, and more particularly to a method for highly active polymerization of polyethylene using a modified magnesium halide as a catalyst carrier.

It is well known that magnesium halide is used as a carrier material to support transition metals in highly active polymerization catalysts for polyolefins, and when transition metals are directly supported on magnesium halide, the amount supported is very small and the activity is low. It turns out it's not expensive.

Furthermore, various proposals have been made to overcome this drawback, such as pre-treatment before contact with transition metals, or the presence of various compounds during reaction with transition metals.

For example, the raw material is a magnesium halide electron donor adduct produced by coordinating an electron donor such as water, alcohol, or ester to magnesium halide (Japanese Patent Publication No. 46-34092, Japanese Patent Publication No. 48-19794). (Japanese Patent Publication No. 53-17
No. 96, JP-A No. 49-88983), those using activated anhydrous halogen-ratio magnesium obtained by activation using a ball mill, etc., or by heating alcohol and water adducts (Japanese Patent Publication No. 47-41676) )
, one in which an alcohol pretreated product of magnesium dihalide is reacted with an organic metal of Groups 1 to 3 of the periodic table (JP-A-49-119980), and one in which magnesium dihalide and aluminum chloride are co-precipitated from an alcohol solution. (Japanese Unexamined Patent Publication No. 130692/1983) is known.

However, the method of forming a pre-treated adduct with an electron donor requires a great deal of care and effort in adjusting the amount of addition and other treatments, and further processing them increases the number of steps. All of these methods have advantages and disadvantages, such as a decrease in activity even if the amount of titanium supported increases, or a low bulk specific gravity of the resulting polyethylene.

In the process of conducting detailed studies on highly active polymerization of ethylene using magnesium chloride, the present inventors found that the presence of a tetraalkoxy silicon compound when supporting titanium halide on magnesium chloride resulted in a slight increase in activity. However, in view of the fact that the amount of titanium supported was still small and the bulk specific gravity of the resulting polyethylene did not improve, further studies were conducted.

As a result, they found that by treating magnesium chloride with tin halide and alcohol and then carrying out a similar supporting treatment, the activity significantly increases and the bulk specific gravity of polyethylene also increases, leading to the completion of the present invention.

That is, the present invention provides a method for producing polyethylene using a catalyst containing (A) a reaction product of a magnesium compound and a titanium halide and (B) an organoaluminum compound, in which magnesium chloride is used as a captive component.
．． A solid product obtained by contacting and reacting with a tin halide in an amount of 1 molar or more and an alcohol in a molar amount of 0.1 times or more, and then reacting the resulting solid substance with a titanium halide in the presence of a tetraalkoxysilicon compound. The present invention provides a method for producing polyethylene, which is characterized by using the following method.

As the magnesium chloride used in the present invention, unactivated magnesium chloride such as commercially available anhydrous magnesium chloride is sufficient, but it is of course possible to use anhydrous magnesium chloride activated by a conventionally known method.

Furthermore, a mixture with a known metal compound carrier that does not inhibit ethylene polymerization may be used.

The component (A) in the catalyst used in the method of the present invention is adjusted as follows.

That is, the magnesium chloride described above is usually first dispersed in an inert solvent.

The amount of dispersion is not particularly limited, but for convenience of operation, the amount of dispersion is
It is preferable to set it as 50-500g per 1.

Subsequently, tin halide and alcohol are added to this dispersion system and reacted with stirring at a predetermined temperature and time to modify the magnesium chloride.

The reaction temperature at this time is usually 60 to 140°C, which is effective and the resulting catalyst has a high polymerization activity, and the bulk specific gravity of the polyethylene produced using this catalyst is also high, which is preferable.

The reaction time depends on the reaction temperature, but if the temperature is 60° C. or higher, the reaction time may be at least 0.5 hours.

Note that the order of contacting the three components in the above reaction is not particularly limited to this, but can be carried out in two steps, such as first reacting magnesium chloride and tin halide, and then adding alcohol to the reaction system. You can do it separately.

The halogen ratio tin used in the above reaction is SnC1
4, SnBr4, SnI4, SnCl2, SnBr2, etc., and these may be used alone or as a mixture.

Among them, SnC14 is most preferably used.

As mentioned above, the amount of tin halide added is at least 0.1 times the molar amount of magnesium chloride.

There is no particular upper limit to the amount added, but if too much is used, the polymerization activity of the finally prepared catalyst will not be improved, nor will the bulk specific gravity of the resulting polyethylene be increased.

Therefore, since using a large amount of tin halide would rather waste the reactant, the amount used is usually 4 times the molar amount or less.

If the amount of tin halide added exceeds the lower limit of this range, the catalyst activity and the bulk specific gravity of the produced polymer will not be sufficiently improved.

On the other hand, the alcohol used in the above reaction is a linear or side chain aliphatic or aliphatic alcohol, and particularly preferred is a primary or secondary alcohol having 1 to 5 carbon atoms.

Specifically, methanol, ethanol, propanol, isopropanol, butanol, imbutanol, amyl alcohol, octanol, etc. can be mentioned.

The amount of alcohol added is at least 0.1 times the molar amount of magnesium chloride.

There is no particular limit on the upper limit of the amount to be added, but since using a large amount will waste the titanium compound as described below, the halogen ratio is usually around the same amount as the halogen contained in tin.

If the amount of alcohol used is lower than this lower limit, the desired improvement in polymerization activity or bulk specific gravity of the polymer cannot be sufficiently expected.

The solvent used in the above reaction is not particularly limited as long as it is inert and does not react with the above magnesium chloride, tin halide, and alcohol. It will be done.

Specifically, butane, pentane, hexane, hebukun, cyclohexane, etc. are suitable.

Although the reaction using a solvent as described above is a preferred embodiment of the present invention, it is also possible to carry out the reaction without a solvent.

In this case, for example, the predetermined proportions of the above-mentioned Shioyama magnesium, halogen ratio tin, and alcohol may be directly mechanically mixed and reacted using a ball mill or the like.

The modified magnesium chloride solid material thus obtained is used in the next reaction either in the reaction dispersion as it is or after washing and separating the modified solid.

Note that the modified product may be further treated with an organoaluminum compound and used in the next reaction.

Component (A) in the catalyst used in the method of the present invention is a substance obtained by reacting the above-mentioned modified magnesium chloride with a titanium halide in the presence of a tetraalkoxy silicon compound.

Examples of the tetraalkoxy silicon compound used here include tetramethoxysilane, tetraethoxysilane, and tetrabutoxysilane, and these may be used alone or in combination.

Further, titanium halides that can be used include tetravalent, trivalent, and divalent halogen-containing titanium, and specifically, T
iBr4, TiCl4, Ti(OR)Cl3, Ti(O
R)2Cl2, Ti(OR)3c1, TiBr3, Ti
Cl3, TiCl2, etc. (where R represents an alkyl group).

), and those that do not contain a large amount of alkoxy groups are particularly preferred.

The reaction of the above modified magnesium chloride with the tetraalcoquine silicon compound and the titanium halide is usually carried out in a hydrocarbon solvent, but it is also possible without a solvent.

When carried out in a solvent, a predetermined amount of the tetraalkoxy silicon compound and titanium with a halogen ratio can be added directly to the reaction solution for producing the modified product by the solvent method, but it is also possible to add the tetraalkoxy silicon compound and titanium with a halogen ratio directly to the reaction solution for producing the modified product by solid washing and separating the reaction solution for producing the modified product. It is also possible to add the above-mentioned tetraalkoxy silicon compound and titanium halide to a dispersion liquid in which the modified product is separated in an inert solvent again.

After the addition, the mixture is stirred and reacted at room temperature to 120°C, preferably 60 to 100°C, for 30 minutes or more under normal pressure or increased pressure.

In addition, before contacting titanium halide under the above conditions, the modified product and tetraalkoxy silicon compound were mixed at a ratio of 60 to 10
The contact reaction may be carried out at 0°C for 30 minutes to 2 hours.

On the other hand, in the case of a solventless reaction, mechanical mixing using a ball mill or the like may be performed at the above temperature and time.

The amount of the tetraalcoquine silicon ratio compound used in this reaction was 0.1 to the magnesium chloride used in the same manner as above.
The amount should be more than twice the molar amount.

The proportion of titanium halide to be added is at least the equivalent molar amount, preferably in excess, relative to the amount of magnesium chloride used.

Specifically, the amount is 1 to 20 times the molar amount, preferably 2 to 15 times the molar amount, especially when added to a system in which alcohol, tin halide, or a reactant thereof is present, such as when the modified product pretreatment solution is used as it is. There is a large excess of the tin halide used, approximately 5
It is preferable to use twice the molar amount or more.

If the amount of titanium halide used relative to these residual materials is small, the resulting polyethylene will not have sufficient bulk specific gravity or polymerization activity.

After carrying out the above reaction, solid components are separated and washed from the reaction product.

This washing is carried out using an inert hydrocarbon solvent having 5 to 10 carbon atoms, such as pentane, hexane, cyclohexane, heptane, etc.

The washed solid product is further dispersed in an inert hydrocarbon solvent in an inert gas at an appropriate concentration and used as a catalyst component.

Note that the solid product after washing may be further treated with organoaluminum and then made into a dispersion as described above. In this case, the polymerization activity of the catalyst and the bulk specific gravity of the polyethylene to be polymerized are further increased.

The organoaluminum compound that can be used in this case may be the same as the organoaluminum compound as the catalyst component (B) described later, or may be different.

It is sufficient that the amount used is approximately equal to or more than the amount of supported titanium.

In the method of the present invention, the reaction product of the above-mentioned modified magnesium chloride, the above-mentioned alkoxy-containing silicon compound, and titanium halide is used as a captive component, and the organoaluminum compound is used as the (B) component (A), (B). This is carried out using a catalyst consisting of both components.

In polymerizing ethylene, a dispersion of component (A) and an organic aluminum compound as component (B) are added as catalysts to the reaction system, and then ethylene is introduced into the system.

There are no particular restrictions on the polymerization method and conditions, and solution polymerization,
Both suspension polymerization and gas phase polymerization are possible, and both continuous polymerization and discontinuous polymerization are possible.

For example, in the case of solution polymerization or suspension polymerization, the amount of the catalyst component added is 0.001 to 50 mmol/l for component (A), and 10 to 50 mmol/l for component (B) (based on the At component).
500 (molar ratio), preferably 30 to 200 (molar ratio)
shall be.

Further, the ethylene pressure in the reaction system is preferably normal pressure to 50 kg/cm, and the reaction temperature is preferably normal temperature to 200°C.

Molecular weight adjustment during polymerization can be carried out by known means, such as hydrogen.

Examples of the organoaluminum compound which is the component (B) of the catalyst used in the method of the present invention include trialkylaluminum compounds such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triimbutylaluminum, and trioctylaluminum, and diethylaluminum monochloride, Dialkyl aluminum monohalides such as diimpropyl aluminum monochloride, diisobutyl aluminum monochloride, and dioctyl aluminum monochloride are suitable.

The types of polyethylene that can be polymerized by the method of the present invention include not only ethylene homopolymers, but also copolymers of ethylene and small amounts of α-olefins such as propylene, butene-1, hexene-1, and the like.

Note that the catalyst used in the method of the present invention may further contain an organic metal such as organic zinc.

According to the method of the present invention as described above, an effectively modified carrier can be obtained through a complex reaction between tin halide, alcohol, and magnesium chloride, although its actual nature is unknown.

Furthermore, this carrier, a modified magnesium chloride, exhibits high polymerization activity by effectively supporting silicon compounds and titanium, although it is unclear in what manner. is obtained.

Therefore, according to the method of the present invention, high-quality, bulky and heavy high-density polyethylene can be produced extremely efficiently and economically.

Next, the method of the present invention will be explained in more detail with reference to Examples, Reference Examples, and Comparative Examples.

Example 1 (1) Production of catalyst 10.5 mmol of anhydrous magnesium chloride was suspended in 50 ml of n-heptane, 145.3 mmol of SnC was added thereto, and then 21.0 mmol of ethanol was added and the temperature was raised to 80°C.

After reacting for 1 hour, the mixture was cooled to room temperature, the supernatant liquid was removed, and the mixture was washed once with 100 ml of Kurmalheptane, and 50 ml of normal heptane was added thereto to prepare a dispersion.

si(OC2H5) to the dispersion 45. 3 mmol and 45 ml of TiCl were added and reacted under reflux for 3 hours.

After cooling, the supernatant liquid was removed and washing was repeated three times using 100 ml of n-heptane each time, and finally 200 ml of n-heptane was added to form a catalyst suspension.

The amount of titanium supported was 25 mg - Ti/g - carrier.

(2) Polymerization of ethylene Thoroughly dry a 1 liter autoclave, add 400 ml of normal hexane under argon, and add 2.0 mL of triethylaluminum.
0 mmol and the catalyst dispersion prepared in (1) above were used in an amount equivalent to 0.02 mmol as titanium atoms, and the temperature was raised to 80°C.

Next, polymerization was carried out at 80° C. for 1 hour while continuously supplying ethylene under hydrogen pressure of 3 kg/ca and ethylene pressure of 5 kg/c4.

The polymer was separated and dried to obtain 249 g of polyethylene.

Polymerization activity is 259k per hour for 1g of titanium particles
g, and the melt index of polyethylene is 1.2
The bulking weight was 0.32.

Examples 2 to 5 In Example 1, SnC14, ethanol and Si
A catalyst was prepared in the same manner as in Example 1, except that the amount of (OC2H5)4 used was varied, and ethylene was polymerized.

The results are shown in Table-1. Examples 6 to 9 (1) Production of catalyst 10.5 mmol of anhydrous magnesium chloride was suspended in 50 ml of n-heptane, predetermined amounts of SnCl4 and alcohol were added thereto, and the temperature was raised to 80°C.

After reacting for 1 hour, a predetermined amount of Si was added to the reaction solution.
(OC2H5)4 and TiCl4 were added and reacted under reflux for 3 hours, and a catalyst was produced in the same manner as in Example 1 (1).

The results are shown in Table-2.

(2) Polymerization of ethylene The catalyst dispersion prepared in (1) above has 0 titanium atoms.
．． Example 1 (except that an amount equivalent to 0.01 mmol was used)
Ethylene polymerization was carried out under the same conditions and method as in 2).

The results are shown in Table-2. Comparative Example 1 10.5 mmol of anhydrous magnesium chloride was suspended in 50 ml of normal hebutane, and S ri C 14 5
．． 3 mmol was added, followed by 21.0 mmol of ethanol, and the temperature was raised to 80°C.

After reacting for 1 hour, 45 mA of TiCl was added and the reaction was carried out under reflux for 3 hours.

Thereafter, a catalyst was produced in the same manner as in Example 1, and ethylene was polymerized using the same conditions and method to obtain 141 g of polyethylene.

In this case, the amount of titanium supported was 28 mg-Ti/g of one carrier, and the polymerization activity was 147 titanium atoms per hour.
It was kg.

The melt index of the obtained polyethylene was 24.
The bulk specific gravity was 0.32.

It was found that the presence of a tetraalkoxy silicon compound when supporting titanium significantly increases the activity.

Comparative Example 2 In Example 1, C was substituted for Si(OC2H5)4.
Example 1 except that 2Si(OC2H5)2 was used.
A catalyst was prepared under the same conditions and method as above, and ethylene was polymerized.

In this case, the amount of titanium supported is 38■-Ti/g per carrier, and the polymerization activity is 83 kg per 1 g of titanium atom and 1 hour.
Met.

The melt index of the obtained polyethylene was 1.
2, and the bulk specific gravity was 0.25.

Comparative Example 3 A catalyst was produced under the same conditions and method as in Example 1, except that SiC14 was used instead of SnCl4, and ethylene was polymerized.

In this case, the amount of titanium supported is 88 ■-Ti/g-carrier, and the polymerization activity is 63.5 k per 1 g of titanium atom and 1 hour.
It was g.

The melt index of the obtained polyethylene was 0.
63, and the bulk specific gravity was 0.16.

The bulk specific gravity was significantly lower than when using SnCl4 according to the present invention.

Comparative Example 4 In Example 1, a catalyst was produced under the same conditions and method as in Example 1, except that SnC14 was not used, and ethylene was polymerized.

In this case, the amount of titanium supported was 69 mg-Ti/g per carrier, and the polymerization activity was 91 mg per hour per 1 g of titanium atom.
It was kg.

The melt index of the obtained polyethylene was 1.
4, and the bulk specific gravity was 0.26.

Comparative Example 5 In Example 1, SnC14 was not used and Si(OCH5)4 was replaced with SiC14 or SnC14.
A catalyst was produced under the same conditions and method as in Example 1, except that Cl4 was used, and ethylene was polymerized.

Claims (1)

[Claims] 1. In a method for producing polyethylene using a catalyst containing (A) a reaction product of a magnesium compound and a titanium halide and (B) an organoaluminum compound, 0.1 times the mole of magnesium chloride as the component (8) is used. Using a solid product obtained by contact reaction with a tin halide in an amount or more and an alcohol in a molar amount or more of 0.1 times or more, and then reacting the generated solid substance with a titanium halide in the presence of a tetraalkoxysilicon compound. A method for producing polyethylene characterized by: